Since the earliest development of electronic equipment, manufacturers have recognized the need for sturdy housing assemblies within which to mount or store the electronic equipment or which form a case for mounting electronic circuitry and components. With the increased sophistication of equipment and the miniaturization of components, more and more electronic equipment have been constructed as portable systems which may be transported from location to location for use by the operator. Indeed, due to the reduction in power demands of these systems, many types of electronic equipment now include an internal power supply in the form of a rechargeable battery pack.
Perhaps the field where the reduction in size and weight of electronic equipment has been most dramatically felt, in recent years, has been in the computer industry. In the early days of this industry, computers were based on vacuum tube technology and had limited computing capacity even though the equipment itself occupied thousands of cubic feet of storage and had elaborate cooling systems. Present technology has allowed miniaturization of computer systems, and, by the mid 1980's, computer systems having significant processing and storage capabilities were reduced in size so as to make practical the portability of such systems. Initially, the "portable" computers were still quite bulky and cumbersome to transport and still required enough power so that they could not readily be powered by conveniently portable battery packs. Within just a few years, as of the date of this disclosure, further advancements in circuit technology has resulted in truly portable computers having significant computing capabilities and substantial memory capacity.
At the time of this disclosure, three main types of transportable computers are dominant in the industry. At one end of the spectrum are the "portable" computers which may weigh on the order of six to eight kilograms and have a footprint of 0.1-0.15 meter.sup.2. At the other end of the spectrum are the note pad computer/calculators which weigh anywhere from several hundred grams to about one kilogram; these units can have foot prints on the order of fifty to one hundred centimeter.sup.2. In between the portable computers and the note pad computer/calculators reside computer systems which may truly be deemed "lap top computers". These computers may weigh on the order of four to six kilograms and have foot prints on the order of 0.1 meter.sup.2.
The present invention principally concerns the portable and lap top computers. In each of these units, the size of the housing and the associated keyboards is becoming dictated by the ergonomics of interaction with the human body as opposed to the limitations of circuitry technology. That is, the size of the keyboard is dictated by the size of the human hand and fingers in operating the keys while the display size must be large enough so that visual output is of sufficient size and content to be meaningfully seen and comprehended. It is anticipated that the size of these units will remain relatively constant so that advancements in circuit technology will result in computers of the same size having greater memory and processing capabilities.
Currently, housing constructions for both portable and lap top computers is dominated by the "clam shell" case, an example of which may be seen in U.S. Pat. No. 4,571,456 issued Feb. 18, 1986 to Paulsen et al. Here, a central unit is provided which houses both a keyboard and the processing circuitry for the computer system. A lid is hingedly secured to this central section so that the lid folds over and protects the keyboard, and this lid may be latched into the closed position. When used, the lid is unlatched and tilted at an angle with respect to the central housing. This lid carries a display panel for the computer as a visual output allowing the user to receive visual output corresponding to the processing being performed by the computer. Virtually all portable and lap top computers utilize this general clam shell construction, with different manufacturers making slight modifications for functional operation and/or aesthetic appearance.
A problem with respect to the clam shell housing construction, however, is that the central section has a fairly large footprint when placed on a desk or other support surface. Further, since the display panel and the keyboard contained within the central section are mechanically connected, the distance between the keyboard and the display may not be varied to accommodate individual user preference Further, a problem arises with many of these units in that a separate support surface is necessary for comfortable use of the computer system. That is, typically, the user must place the unit on a desk, table or other surface so that the user can sit at a chair while operating the system. This defeats the "lap top" concept wherein a user can hold the unit on his/her legs while operating the computer. There is therefor need for alternate and improved computer case construction which can help to eliminate some of these disadvantages.